#单继承：子类继承父类的所有属性和方法
class Amphibian:
     name = "两栖动物"        
     def features(self):
          print("幼年用鳃呼吸")
          print("成年用肺兼皮肤呼吸")
class Frog(Amphibian):
     def attr(self):
          print(f"青蛙是{self.name}")
          print("我会呱呱叫")

#
frog = Frog()
print(frog.name)
frog.features()
frog.attr()
